Numbers 32:17-27

17 but we will take up arms, ready to go before the people of Israel, until we have brought them to their place; and our little ones shall live in the fortified cities because of the inhabitants of the land.
18 We will not return to our homes until the people of Israel have inherited each his inheritance.
19 For we will not inherit with them on the other side of the Jordan and beyond; because our inheritance has come to us on this side of the Jordan to the east."
20 So Moses said to them, "If you will do this, if you will take up arms to go before the LORD for the war,
21 and every armed man of you will pass over the Jordan before the LORD, until he has driven out his enemies from before him
22 and the land is subdued before the LORD; then after that you shall return and be free of obligation to the LORD and to Israel; and this land shall be your possession before the LORD.
23 But if you will not do so, behold, you have sinned against the LORD; and be sure your sin will find you out.
24 Build cities for your little ones, and folds for your sheep; and do what you have promised."
25 And the sons of Gad and the sons of Reuben said to Moses, "Your servants will do as my lord commands.
26 Our little ones, our wives, our flocks, and all our cattle, shall remain there in the cities of Gilead;
27 but your servants will pass over, every man who is armed for war, before the LORD to battle, as my lord orders."
Revised Standard Version of the Bible, copyright 1952 [2nd edition, 1971] by the Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.